Means for delivering preheated air to combustion chambers



G. VAN DAAM Nov. 5, 1929.

1,734,545 MEANS FOR DELIVERING PREHEATED AIR TO COMBUSTION CHAMBERSFiled Dec. 31, 1927 g 4 J )l p n .Q r 2 m a emufl/ w r a E? 7 I w J 1 IQ n a. r 6 6 0 Patented Nov. 5, 1929 ennnrr VAN-,DAAM, or BUFFALO, NEWYoRx MEANS FOR nnmvnnrnernnnna'rnn AIR ro COMBUSTION CHAMBERSApplication filed December'ifl, 1927. Serial No. 243,900.

My invention relates to delivering preheated air to combustion chambers,andis especially applicable to the combustion of coal where the unburnedgases rise from the fuel bed and are mixed with the preheated airdelivered thereto to facilitate the combustion of said gases.

The invention also comprises the control of the flow of air to bepreheated and delivered to the combustion chamber in order to meet theconditions of the fuel bed and the temperature of the combustion chamber'so that when the combustion chamber is relativelycold the flow of airwill be restricted and as the chamber becomes heated the how of air willbe relatively increased.

Referring to the drawings which illustrate merely by way of example,suitable means for effecting the invention Fig. 1 is a side elevation ofthe air heating element.

Fig. 2 is a longitudinal central section of same.

Fig. 3 is an elevation of the discharge end.

Fig. 4 is an elevation of the inlet end.

Fig. 5 is a detail in part section on an enlarged scale of thethermostat control unit.

Fig. 6 is a similar view of a modification.

Fig. 6 is a cross-section of same.

Similar numerals refer to similar parts hroughout the several views.

The heating element or body8 is preferably an integral casting inhelical formation, but provided with an axial reinforcing extension 9integral with the spiral. The spiral is cast with double helical walls10 and 11 forming a space 12 between these walls which provides ahelical passage in annular cross-section from one end to the other. Theinner space 13 enclosed in the inner wall 11 is a closed air space.

The device is secured at the inlet end to the door 14 of the combustionchamber and extends therefrom into the combustion chamber above the fuelbed.

The means for securing the heating ele ment to the doo-ror wall of thecombustion chamber comprises the flanged element 15 Y which is threadedon to the nozzle 16 of the heating element. The flange 17 engages theinner face of the door 14 or wall of the coinbustion chamber. Theelement 15 is provided with the threaded nozzle formation 18 whichextends through the door 14 or wall of the combustion ch amber, andreceivesthe threaded end of the inlet formation or head 19, and forms aclamp therewith.

The discharge end of the heating element is provided with the cap 20threaded thereon and having a series of air discharge vents 21.

Any suitable thermostat controlled valve is provided for automaticallycontrolling the inlet of air to element 8.

InFig. 2 is shown a strip 28 secured to the inner recessed side ofelement 15, and to which is secured the valve rod 24 carrying the valve25. This rod 24 is responsive to changes of temperatureto expand orcontract to operate the valve25, sothat a greater supply ofair isadmitted to the element 8, as its temperature increases.

In accordance with the arrangement shown in Fig. 5, a cap 22, providedwiththe peripheral inlet ports 23 is'disengageably secured to the innerside of element 15. Through the endof the cap 22 projects the axiallyextending and movable stem or spindle 24; to the innerend of which issecured the valve 25, controlling the passage of air into the heatingelement 8. A helical bimetallic thermostat element 26 is secured atoneend to the valve stem or'spindle 24 near its outer end, and at itsother end to the cap 22. As'this helix is within the passage of theheating element, it responds to variations of temperature to control thevalve.

In the modification shown in Figs. 6 and 6 the bi-inetallic thermostatelement 27 is in the form of a flat ribbon bent into a spiral; one endsecured to a stationary support, the

other end secured to the spindle or valve stem 28, so that the action isto rotatethe spindle instead of moving it longitudinally. The rotatingspindle 28 mo es the valve 29 to bring its ports 30 into and out ofregister with ports 31.

It will be noted that, in accordance with this arrangement, the valveand its thermostat control forms with the cap 22 a selfcontained unitwhich is readily and disengageably secured in position.

It will be noted that the annular and helical air passage-way 12,confined between the walls 10 and 11, is of comparatively narrowcross-section and is almost entirely surrounded by the products ofcombustion in the combustion chamberand, due to its c'omparatively longand tortuous course, the air passtherethrough is heated approximately tothe temperature of the combustion chamber before discharging through thevents 21.

hat I claim is 1. An air heating element for combustion chambers,comprising a body providing an annular air passage in helical formationextending from one end of said element to the other, and provided withan air inlet atone end and air discharge vents at the other end andmeans for supporting said element at its inlet end with the dischargevents-delivering to the combustion chamber.

2. In a. device of the character described, the combination of a heatingelement comprising two concentric tubes in helical for mation, having anaxial reinforcing extension integral therewith and forming a passagebetween the wallsof said'tubesfrom one end of the element to the other,and provided with an inlet at one end and discharge vents at the otherend and means for supporting the element at its inlet'end.

3. In a device of the character described, the combination of a heatingelement comprising two concentric tubes in helical formation forming apassage between the walls of said tubes from one end'of the element tothe other, and provided with an inlet at one end and discharge vents atthe other'e'nd, means for supporting the element at its inlet end, and aself-containing thermostat controlled valve unit disengageably securedin the inlet passage of the heating element.

l. In a device of the character described, the combination of a heatingelement comprising two concentric tubes in helical formation, providinga passage between the walls of said tubes from one end of the element tothe other, and provided with an inlet at one end and discharge vents atthe other end, means for supportingthe element at its inlet end, and aself-containing valve controlling thermostat unit disengageably securedin the air intake passage to the heatingunit.

5. In a device of the character'described, the combination of a heatingelement comprising two concentric tubes in helical formation, providinga passage between the walls of said tubes from one end of the elen't tothe other, and provided with an inlet at one end and discharge vents atthe other end, means for supporting the element at its inlet end, andavalve controlling thermostat unit, comprising an 'apertured ca'p,avalve, a valve spindle and abi-Inetallic coil associated with the cap,said cap being disengageably secured in the inlet passage of the heatingelement.

6. In a device of the character described, the combination of a heatingelement comprising two concentric tubes in helical formation, providinga passage between the walls of said tubes from one end of the element tothe other, and provided with an inlet at one end and discharge vents atthe other end,

means for supporting the element at its inlet end, comprising a flangedelement threaded Onto said inlet end and an air intake head threadedonto the fiangedelement to form a clamp with a supporting wall.

7. Ina device of the character described, the combination of a heatingelement comprising two concentric tubes in helical formation, providinga passage between the walls of said tubes from one end of the element totheother, and provided with an inlet at one end and discharge vents atthe other end, means for supporting the element at its inlet end, and aself-containing valve controlling thermostat -unit, comprising anapertured cap, a valve, a valve spindle and a bimetallic coil forrotating the spindle associated with the cap, said cap beingdisengageably secured in the inlet passage of the heating element.

GERRIT VAN DAAM.

